1. Field of the Invention
This invention relates to a carrier for retaining an integrated circuit (IC) chip in place during final manufacturing and testing of the chip. More particularly, it relates to a carrier for an IC chip having a cylindrical can body with a number of electrical leads projecting from the bottom of the can in a circular pattern.
2. Description of the Prior Art
Carrier devices are known for integrated circuit (IC) chip cans wherein the electrical leads projecting from the bottom of the can extend through D-shaped holes in the base of the carrier. These holes retain the leads in place. However, the use of such D-shaped holes results in bending or scraping of the soft solder electrical leads during manual or machine insertion and removal of the can from the carrier.
Other carrier devices are known in which a single arm extending from the carrier is snapped over a flange on the lower perimeter of the can to keep it in place. FIG. 1 is a cross-sectional view of a typical prior art carrier for a can-type IC chip having such a single arm. In FIG. 1 an IC can 10 has electrical leads 12 extending from its lower end 14, a stand-off 15 projecting from its lower end, and a flange 16 on the perimeter of lower end 14. Can 10 is retained in the carrier by a single flexible arm 18 having a hook 19 on its arm end 20 projecting therefrom that engages flange 16. Leads 12 are received by holes 13 in a tapered section 18 and in a base 21. A tapered first section 18 projects from base 21 and has a flat top end 22 upon which stand-off 15 of can 10 sits. Base 21 has an upper cylindrical base section 24 and a lower cylindrical base section 26. A platform 28 attached to base 21 at the junction of upper base section 24 and lower base section 26 is used to stabilize the carrier during manufacturing and testing procedures.
A major disadvantage with carriers like the one depicted in FIG. 1 is that single flexible arm 18 places an unbalanced load on can 10, causing the soft solder leads 12 to bend. Leads 12 normally are in a circular pattern that is concentric to the circumference of cylindrical can 10. Prior art devices bend these leads and thus disrupt this concentricity. After the can has been removed from the carrier, the leads typically must be laboriously, manually straightened to reestablish this concentricity before the can may be used in other operations.
A second disadvantage of such prior art devices like the one depicted in FIG. 1 is that flexible arm 18 extends too far above the upper surface 17 of flange 16 and thereby obscures a portion of the can body so that identifying information cannot be printed on the side of can 10 while it is in the carrier.
Other IC chip carriers are known for flat pack or DIP chips. In U.S. Pat. No. 4,379,505 issued Apr. 12, 1983 to Alemanni, and U.S. Pat. No. 4,591,053 issued May 27, 1986 to Alemanni, four resilient retaining fingers are used to retain the flat pack by contacting its outermost leads. The disadvantage of this approach is that it may bend or otherwise harm the soft leads.
U.S. Pat. No. 3,746,157 issued July 17, 1973 to L'Anson discloses a carrier for retaining a flat pack using a snap-in retaining clip, the underside of which is plated with a conductor material such as aluminum. When the retaining clip is in place, this undersurface bridges the conductors of the flat pack, shorting them to one and other. Of course, this approach is not suitable for operations where the leads should not be shorted.
Other carriers are known for retaining flat packs and DIPs. See U.S. Pat. No. 4,556,145 issued Dec. 3, 1985 to Putnam; U.S. Pat. No. 3,892,312 issued July 1, 1975 to Tems; and U.S. Pat. No. 3,652,974 issued Mar. 28, 1972 also to Tems. However, none of these carriers is suitable for retaining a cantype body.